Conventionally, while sealing sealing-fluid (sealed fluid) including slurry, there is a possibility that the slurry accumulates between parts of the apparatus, and a possibility that solidified material of the sealing-fluid adheres on a seal surface or clogs a space between the parts of the apparatus. Therefore, for such sealing-fluid, especially for liquid which deposits when it leaks into the atmosphere, it is necessary to execute quenching to wash deposited material away. To do this, an extra seal for quenching fluid becomes necessary, so that a double mechanical seal in which two mechanical seals are arranged in a linear manner is conventionally general for the seal.
Further, an another mechanical seal device is also disclosed for the seal, the mechanical seal device having a constitution that a flashing passage is provided in a seal cover, and inner circumference surfaces of a stationary seal ring and a rotary seal ring on which the sealed fluid contacts are washed with flashing fluid (refer PCT International Publication WO2006/137305 (Patent Document 1)).    Patent Document 1: PCT International Publication WO2006/137305